"...a misguided group, I will call the Sour Grapes Club(SGC)..."

As a non-native English speaker I have to ask deeper for the meaning of "sour grapes":
it not only means grapes which became sour but is used as a paraphrase for the "envy of those without possessions" (translated directly) - correct?

So does this mean I as a member of the SGC have no possessions while those who are not member own possessions?
This confuses me, because so far I thought that all those who attack the Company for EVERYTHING it did in the last ten, twenty years have lost their possessions, while those who defend the BoD with their rose coloured pants, socks and glasses received royal checks and have made tons of money with this stock...?

Please enlighten me anyone what the club I'm surprisingly member of now is REALLY all about because my wife will surely ask me, what I'm doing there.

TIA